A rotary disc valve for inflating and deflating pressure cells in a therapeutic sleeve is disclosed in U.S. Pat. No. 5,014,681, incorporated herein by reference. This rotary disc valve comprises two discs: a stator disc with fluid flow ports connectable to a compressor and to the pressure cells, and a rotary distributor disc, the two discs contacting sealingly along a planar interfacing surface perpendicular to the axis of rotation. The ports of the stator disc open at the interfacing surface. The rotary distributor disc has a plurality of U-channels and through-going windows also opened at the interfacing surface. The channels and windows are configured so that during rotation of the rotary distributor disc, the compressor flow is successively directed, through the appropriate ports, to inflate the corresponding pressure cells, which are then successively opened to die atmosphere, all this following a predetermined sequence.
JP 01145474 discloses a rotary disc valve with a similar function where the stator comprises two discs fixed with respect to each other, the stator discs slidingly contacting a rotor distributor disc disposed therebetween. The rotor disc has U-channels and through holes connecting the ports of the stator in various combinations during one turn of the rotor distributor disc.
U.S. Pat. No. 4,614,205 discloses a multiport rotary disc valve with a similar function of simultaneous interconnection of a plurality of conduits in accordance with a predetermined cycle. The stator and the rotary distributor in this rotary valve are assemblies each comprised of two parallel plates or discs. The rotary assembly is sandwiched between two parallel plates of the stator assembly. Crossover pipes extend between the rotor plates to form either U-channels or through-passages similar to the above-cited designs.
The known rotary disc valves are capable of performing one predetermined cycle (sequence) of connections between the stator ports. The connections may be varied in time by controlling the rotational velocity and position of the rotor, but their order is determined by the pattern of the channels in the rotor and the stator.